The interior mirror trim pieces are held in with 2 screws. (Thanks to Ricky B for this photo).

It's fairly normal for there to be no adhesive patches over these holes which allows the water to flow around
the seal, over the screw head and into the interior. The water then runs down the front leading edge of the
door, over the lower door seal and under the carpet. So, try adding some duct tape over the screw holes.

Wet Under The Rear Carpets

Firstly remove the engine cover, check the seal all the way around, check for debris on the
seal and where the seal touches the car and make sure it is refitted to the car correctly

Consider also that there may have been unusual circumstances that caused a leak near the
front but so much time may have elapsed until you found it that the water moved to the lowest
point (under and behind the seats) and the front part of the carpet had time to dry.

There is a large grommet coming through the bukhead that carries the main wiring loom
from the engine into the cabin. This could be misaligned or damaged and allowing water in.

The rear screen squirter is fed from the front water tank. The hose runs inside the car so there
is always a possibility that the hose could be split. As most of the pipe is below the water tank
you could get a slow syphoning effect which would very slowly empty the tank into the car.